The present invention relates to the field of image processing. More specifically, the present invention relates to methods and apparatus for efficiently and concurrently applying video encoding techniques to convert analog data into digital formats, such as Digital Video (DV) format. This technique is especially suited for widely-used image compression standards that integrate various algorithms into a compression system, such as the standards specified in the DV Standard (DV-SD or the xe2x80x9cBlue Bookxe2x80x9d), which is included herein by reference in its entirety and for all purposes.
The DV format is quickly becoming the standard for many consumer electronic video devices. For example, DV format camcorders can now be found with more frequency and at more competitive prices than the conventional analog 8 mm and VHS camcorders. At the same time, DV camcorders provide advantages which are inherent to digital technology, such as high quality of video and sound, digital filtering, digital error correction, and the like. DV provides quality at or higher than the high-end of the conventional analog camcorders such as Hi-8 mm and S-VHS, with much added flexibility. Also, digital format data can be repeatedly copied without loss of quality.
In the DV standard, the compression ratio is expected to be around 5:1. This means that excessive truncations of redundant data are unnecessary and image quality will not be compromised as much as some other digital standards available on the market now. In order to maintain a constant compression ratio, the compression analysis can be performed on the image at its video segment level. Each image frame consists of 270 video segments under National Television System Committee (NTSC) standard. Each image consists of 324 under Phase Alternation System (PAL) standard. Each video segment consists of five (5) macro blocks and each macro block contains six (6) blocks of 8xc3x978 pixels.
The DV standard utilizes the 8xc3x978 blocks in performing compression (also known as, xe2x80x9cframexe2x80x9d compression). This data is provided by digitizing an image frame by frame originally in analog format. The analog image signals can originate from cable TV, analog camcorders, video cassette recorders (VCR""s), and other similar analog sources. After digitization and encoding, the signals representing the image can be utilized by digital devices.
A well known technique in the prior art for compression of digitized data is to apply discrete cosine transform (DCT) to a block of data to transform the data from the spatial domain to the frequency domain. The resulting coefficients in the frequency domain act as weighing factors corresponding to their respective cosine curve. For background part of the image data, coefficients corresponding to higher frequency data will have a lower value. Conversely, coefficients corresponding to lower frequency data will have a higher value.
The transformation from the spatial domain to the frequency domain, however, does not by itself compress the digital data. After digital data is transformed into the frequency domain, an adaptive quantization can be applied to compress the data. In particular, adaptive quantization truncates the coefficients corresponding to high frequency data, and in most cases to zero. In essence, adaptive quantization will compress an image by deleting the extreme details of an image.
As a result, a technique is desirable wherein digital video data can be encoded adaptively.
The present invention provides new and improved apparatus and methods for video encoding, for example, to efficiently and concurrently apply adaptive encoding techniques to convert analog data into digital formats, such as Digital Video (DV) format. A parallel system receives a block of video data and based on the computations and comparisons performed determines the best quantization factor for the block of video data. In an embodiment, the parallel system performs selected operations in parallel to save time and increase speed.
For further understanding of the nature and advantages of the present invention, together with other embodiments, reference should be made to the ensuing detailed description taken in conjunction with the accompanying drawings.